Frequency multiplier



Allg. l, 1933. I F. GER-[H 1,920,194

` FREQUENCY MULTIPLIER Filed Nov. 5, 1929 *gmJ-Lfl-J-LL 5 Patented Aug.1, 1933 Partnr orinar.

FREQUENCY MULTIPLIER Felix Gerth, Berlin-Tempelhof, Germany, ari signorto C. Lorenz Aktiengesellschaft, Berlin- Tempelhcf, Germany ApplicationNovember 5, 1929, Serial No. 404,891, and in Germany November 17, 1928 1Claim.

In order to permit the reception of broadcast radio performances overlarger areas With the type of radio receiver in common use, it has beensuggested that programs be broadcast from a number of stations on thesame Wave length. In using this system a central station transmits astandard or primary frequency to the stations which are to broadcast ona common frequency, and at each transmitting stationthe standardfrequency is uniformly multiplied to the common carrier frequency. Astandard frequency may also be supplied from a central station todifferent broadcasting stations operating on different wave lengths. Inthis case a multiplica.- tion of the standard frequency will, of course,be different at each station. With the known methods endeavors Were madeto choose the frequency transmitted from the central station to thevarious separate transmitting stations as high as possible, in order toget along at the local transmitting station with as low a multiplicationas possible. When the control frequency is transmitted on cable lines,however, the multiplying factor must be chosen rather high, as one isforced by the limiting frequency of the cable to employ a primary orbasic frequency of a low period. Thorough investigations have shown thatit is more favorable not to carry out the multiplication at the localtransmitting station in one step as in the former methods, but inseveral steps. For this purpose it is necessary according to the presentinvention to arrange ahead of the multiplying device an amplifyingdevice and behind the said multiplying device a suitable device for theremoval of any disturbances, which will take care that merely thedesired multiplied frequency proceeds to the following circuit.

To the device for removing any disturbances are connected severalsimilar devices for amplifying, multiplying and removing thedisturbances, in a cascade-like manner.

An embodiment of the arrangement according to the invention isillustrated by Way of example in the drawing.

Figure l represents diagrammatically the arrangement of the varioussteps.

Figures 2 and 3 are diagrammatic views amplifying device, and

Figure 4 shows diagrammatically the operation of the tube.

Referring to Figure 1 it illustrates purely diagrammatically thearrangement of the different steps. At the left side, for instance, afrequency of the r of 2500 cycles is supplied by means of a cable.

vbe explained here.

(Cl. Z-36.)

Naturally the device according to the invention is not limited to thetransmission of frequencies by means of cables. The cable is connectedWith the input circuit of an amplifying device V1. To the output circuitof the amplifying device is connected the stage Sti, consistingaccording to this invention of an amplifying device, a device formultiplying the frequency and a device for removing any disturbances.The frequency multiplied is supplied to an additional stage Stz,designed in the same manner. Between the second stage and thetransmitting apparatus S inserted a further multiplying stage Sta.

The ratio of multiplication of the various steps could be about 1: 9 forthe first step, 1: ,'l for the secondstep and the third step, so thatthere Will result a total factor of multiplication of 1: 9 7 'I or aboutl: 450. With the control frequency of 25Go cycles mentioned the Wavelength radiated would then be approximately 270 metres. During the testsmade the ratio l: 15 has proved the maximum ratio of multiplication of asingle step.'

The arrangement of the individual stages is more fullyy explained inFigures 2 and 3. Figure 2 shows a system of multiplication whichoperates with frequency changers, While the arrangement shown in Figure3 effects the multiplication by means of electronic tubes, whose actionwill be explained hereinafter. The starting frequency of the stage issupplied to the grid of an amplifying tube R1. In the anode circuit ofthe tube or valve is arranged an aperiodic circuit formed of theinductance L1. The amplified oscillations are supplied by means of aninductance coupled to the inductance L2 to the input circuit of themultiplying circuit formed by the inductances L3, L4 and the capacitiesC1 and C2, in which multiplying circuit a saturated iron frequencychanger F is arranged in `lrnovvn manner. The principle of causingimpulses is known per se and need not In order to carry through afurther faultless multiplication in the various steps it is necessary toarrange behind the multiplying circuit a device for removing anydisturbances, which Will merely permit the desired frequency to pass.

At the places of pure Watt tension in the device for removing anydisturbances the circuit for removing such disturbances, formed of theinductance L5 and the capacity C3 is connected, which may preferablyconsist of a large capacity and small inductance, in order to obtain asYgood a removal of disturbances as possible. It is superfluous to referinparticular to the remaining I connection of the input inductance Le,the output inductance L9 and the inductances L7, Ls of the oscillatorycircuit, further the capacities C4 and C5, which are also situated inthe circuit. The neXt stage is then connected to the inductance L9.

In order to ensure a aultless operation of the arrangement shown, it isnecessary to neutralize the ampliying devices in known manner. As inthis instance very high frequencies are concerned, particular importancemust be attached to a good neutralization. In addition the several partsmust be shielded towards each other, as such is indicated by dash anddotted lines in the drawing. The shield A1 comprises the ainn plifyingdevice and the device for multiplying the frequency. The next circuit isprotected by the shield or screen A2, in order to permit of the circuitfor removing any disturbances, consisting of the capacity C3 and theinductance L5, being specially vencased (A3). Special care must beexercised in order to effect the screening or shield A3 for L5 andr C3.The circuit following the circuit for removing any disturbances issurrounded by the shield A4. v

The screening can be eiected, exactly as represented in theillustration, if transmission coils with an interposed shield areused.

In contradistinction to the described arrangement with iron corefrequency changers the embodiment shown in Figure 3 oiers specialadvantages, since the impulse energy required there, must be rather highin order to obtain the saturation of the iron, While in the tubearrangemen represented it is possible to operate on energies, which onlyamount to one hundredth part of the energy requisite for the iron corefrequency changers. Besides, there are Vencountered diiiim culties inthe constructional design of the iron core frequency changers, sincethey are very small. To the amplifying tube R2 is connected v theimpulse tube Rz in the anode circuit, which contains the inductance L10.The grid circuit, containing the coupling inductance L11, will receiveat -land an extremely high negative grid tension from a batteryconnected across these points. The source of tension is preferablybridged by means of a capacity C6. In the anode circuit of the tube issituated a circuit tuned to that frequency at a ninefold multiplication,which circuit is formed of the capacity C7 and the inductance L12. Themode of operation oi the tube is shown in Figure 4. On account of theextremely high grid tension, which in a practical inode of executionwill amount up to several 100 volts, the working point of the tube orvalve is shifted or displaced in such a manner, that only short tensionimpulses will occur in the grid circuit.

The hatched portion of the curve of the grid tension in saidillustration will clearly show the mode of action. To the circuit tunedto the ninth frequency is connected the device for removing anydisturbances in the same manner as in the arrangement ill strated inf.'1i-3^ii.re 2. The encasing of the individual parts towards each otheris efiected with the multiplication of the frequency also by means oftubes in the same manner, as represented in Figure 2.

In order to give a practical example the following Will serve: Ii thestarting energy in the Jrst step is about 100 watt, there will remainavailable yet after the excitation of the impulses and the sifting orscreening about 5 watt only, which are again ampliiied to 1Go watt andsupplied to an additional step. To the third step is `connected the mainamplifying device V2 which will increase to about 200 watt, while thetransniitting apparatus may possess an output of 3 kilowatt.

I claim:

A frequency multiplying arrangement coinn prising a device to which atransmitted primary frequency is supplied characterized in this thatsaid device comprises a pluraiity of stages connected in cascade andeach stage including an aniplier, a frequency multiplier requiring aminimum amount of energy for its operation, conn nected to the outputcircuit of the ampliner and a disturbance remover coupled to the outputcircuit of the multiplier and suppressing substantially all frequenciesexcept a harmonic oi' the frequency impressed on the input oi themultiplier.

FELIX GERTI-I.`

